Conceived by Brooklynite Sam Clay and his Czech refugee cousin Joe Kavalier, The Escapist symbolizes both the youthful imagination of its fictional creators and the era of early comic book superheroes in which it’s based. Although this superhero figure was invented for Michael Chabon’s 2000 novel The Amazing Adventures of Kavalier and Clay, it’s hard to distinguish this masked vigilante from other contemporaneous icons like Superman and the Phantom. After Chabon received the Pulitzer Prize for his novel, he asked comic vets like Will Eisner and Howard Chaykin to bring the imaginary character to life in a series of real-life comics, which have since been published in multiple separate volumes.

Frequently quoted in Dean Koontz’s novels, The Book of Counted Sorrows was considered a mysterious and rare poetry tome for years. But after Koontz began receiving up to 3,000 letters a year inquiring about his reference source, the mega-selling author announced: “There is no such book. I made it up. The way you made up footnote sources for fabricated facts in high-school English reports.” Koontz eventually penned a volume of poetry under the same title, which he has since released in suitably limited quantities to maintain its elusive allure.

Fans of Calvin and Hobbes will recognize the title Hamster Huey and the Gooey Kablooie as the name of Calvin’s favorite bedtime book. Although Bill Watterson intended the story as a background piece that would remain within the comic strip itself, Mabel Barr turned it into a real children’s book about overcoming bullies and learning respect for others. It’s hard to imagine a troublemaker like Calvin begging for such a morally upright tale every night — or Watterson sanctioning the book’s publication, for that matter — but this is nonetheless the realization of a supposed childhood favorite.

First mentioned in Kurt Vonnegut’s 1965 novel God Bless You, Mr. Goldwater, Kilgore Trout is an itinerant, financially bereft science fiction writer who also appears in other Vonnegut staples like Slaughterhouse-Five and Breakfast of Champions. Although this struggling character finds little success in his fictional life, Trout’s oft-referenced novel Venus on the Half Shell was pseudonymously written in 1974 and published under the fake author’s name. Though initially attributed to Vonnegut himself, the book’s real author was later revealed to be Philip Jose Farmer.

The Tales of Beedle the Bard first appeared as a mentioned collection of fairy tales within the Harry Potter books, but, after the oh-so-lucrative series ended, J.K. Rowling decided to expand her Potterverse by bringing this second-hand referenced book to life. Featuring five apparently classic fairy tales for wizard children, The Tales of Beedle the Bard features an introduction by fictional entity/Hogwarts headmaster Albus Dumbledore, who contextualizes the stories within their “historical” epoch, as well as hand-drawn illustrations by Rowling herself.